Abstract: Seven doses of a natural insecticide, Boxus chinensis oil and the anti-juvenoide, precoceneII were topically applied onto larvae, prepupae and adult of the red palm weevil Rhynchophorus ferrugineus and larvae of the palm beetle, Pseudophilus testsceous. Larvae of R. ferrugineus were less tolerance to B. chinensis oil and more tolerant to precoceneII than P. testaceous larvae. LD50 of R. ferrugineus larvae were 0.11mg/insect and 0.66 mg/insect due to effect of Boxus chinensis and precoceneII, respectively. LD50 of P. testaceous larvae were 0.48 mg/insect and 0.42 mg/insect, using the same previous chemicals, respectively. On the other hand larval, pupal and adult duration was shortened when larvae of R. ferrugineus were treated with B. chnensis and precoceneII. Moreover, B. chinensis oil and precoceneII were clearly occurred a morphogenic abnormalities of the treated larvae and adult of R. ferrugineus and larvae of P. testaceous.